The field of the disclosure relates generally to monitoring of vehicle health, and more specifically, to systems and methods for monitoring health of vibration damping components.
In one example, aircraft landing gear may oscillate or shimmy significantly during takeoff or landing rollout at certain speeds due to one or more combinations of runway conditions, usage, design, wear (free play), applied loads, and angular alignment with the runway. This shimmy is undesirable because it induces additional stress into the airframe, can induce premature failure of landing gear components, and is distracting to the crew and passengers.
A typical method to reduce this oscillation/shimmy is via a passive (shock absorber) or active (actuator) pneumatic or hydraulic damper which mechanically links the stationary upper portion of the aircraft gear assembly and the dynamic rotating/pivoting lower portion attached to the wheels. The damper functions to reduce oscillation and shimmy while not impacting the lower gear assembly's motion requirements for shock absorption, steering, and load reduction induced from the alignment of the aircraft with the runway.
Currently it is not possible to determine the functional capability of these dampers via self testing because dynamic loads induced by aircraft landing, take-off or ground maneuver are needed to initiate the shimmy, there are no systems or mechanisms to assess their performance, and the onset of failure is very subtle. Furthermore, there are situations where the crew perceives an aircraft vibration that does not originate from landing gear shimmy, thus inducing an unwarranted maintenance action.
The current maintenance process for such dampers is to wait until evidence of damper failure is unequivocal, as evidenced by a pilot handling report, by visual observation, or by detection of ancillary damage to the landing gear. There are no practical means to determine or predict failure of the damper before witnessing the landing gear shimmy during a landing.